Synthetic Studies and Mechanistic Insight in Nickel-Catalyzed [4+2+1] Cycloadditions
作者:Yike Ni、John Montgomery
DOI:10.1021/ja057741q
日期:2006.3.1
with alkynes tethered to dienes has been developed. A broad range of unsaturated substrates participate in the sequence, and stereoselectivities are generally excellent. Stereochemicalstudies provided evidence for a mechanism that involves the [3,3] sigmatropicrearrangement of divinylcyclopropanes.
involving 1,3-diene, alkyne, and silylene to afford silicon-containing seven-memberedrings was established. In the presence of a rhodium catalyst bearing bis(diphenylphosphino)methane (DPPM), nona-1,3-dien-8-yne derivatives reacted efficiently at 80–110 °C with boryl(isopropoxy)silane or boryl(diethyamino)silane, which reacts as the synthetic equivalent of silylene, to afford 1-silacyclohepta-2,5-dienes (2
建立了铑催化的[4 + 2 + 1]环加成反应,该反应涉及1,3-二烯,炔烃和亚甲硅烷基,以提供含硅的七元环。在带有双(二苯基膦基)甲烷(DPPM)的铑催化剂的存在下,壬基1,3-三烯-8-炔衍生物在80–110°C下与硼基(异丙氧基)硅烷或硼基(二乙氨基)硅烷有效反应,其作为亚甲硅烷基的合成当量反应,得到1-silacyclohepta-2,5-二烯(2,5-二氢-1 H-西勒平)。七元非共轭二烯的区域发散性和化学和立体选择性官能化是通过Cs 2 CO 3或铱催化剂介导的硼氢化作用实现的。
Gold(I)-Catalyzed Oxidative Rearrangements
作者:Cole A. Witham、Pablo Mauleón、Nathan D. Shapiro、Benjamin D. Sherry、F. Dean Toste
DOI:10.1021/ja071231+
日期:2007.5.1
A series of gold(I)-catalyzed oxidative rearrangement reactions of alkynes using sulfoxides as stoichiometric oxidants are reported. The reactions are postulated to proceed through intermolecular oxygen atom transfer from the sulfoxide to gold(I)−carbenoid intermediates. Under the conditions for gold(I)-catalyzed oxidative rearrangement, 1,6-enynes are isomerized to cyclopropyl aldehydes, homopropargyl
An Efficient [4 + 2 + 1] Entry to Seven-Membered Rings
作者:Yike Ni、John Montgomery
DOI:10.1021/ja046147y
日期:2004.9.1
A new nickel-catalyzed procedure for the [4 + 2 + 1] cycloaddition of trimethylsilyl diazomethane with alkynes tethered to dienes has been developed. A broad range of unsaturated substrates participate in the sequence, and stereoselectivities are generally excellent. Three possible mechanisms are proposed, and each involves the generation of a transient nickel carbene species.
Cyclization reactions of a molybdenum carbene complex with 1,3-nonadien-8-ynes